SPRUI04F july 2015 – april 2023
In Example5-3, the expression "q1:q0" means that the first argument into the linear assembly function is a register pair. By the C calling conventions, the pair "q1:q0" symbols are mapped to register pair "a5:a4". When a register pair syntax is used as the argument to a .reg directive (as shown), it means that the two register symbols are constrained to be an aligned register pair when the compiler processes the linear assembler source and allocates actual registers that the register pair symbols map to "r1:r0" as shown.
The compiler supports a register quad syntax (C6600 only) in order to specify 128-bit operands of 128-bit capable instructions in linear assembly and assembly source code. Example5-4 illustrates how you can specify register quads: